bundles/org.simantics.mapping/src/org/simantics/mapping/constraint/instructions/BinaryPredicateSubjectQuery.java

   1 /*******************************************************************************
   2  * Copyright (c) 2007, 2010 Association for Decentralized Information Management
   3  * in Industry THTH ry.
   4  * All rights reserved. This program and the accompanying materials
   5  * are made available under the terms of the Eclipse Public License v1.0
   6  * which accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *     VTT Technical Research Centre of Finland - initial API and implementation
  11  *******************************************************************************/
  12 package org.simantics.mapping.constraint.instructions;
  13
  14 import gnu.trove.set.hash.TIntHashSet;
  15
  16 import java.util.Collection;
  17 import java.util.Iterator;
  18
  19 import org.simantics.db.ReadGraph;
  20 import org.simantics.db.Resource;
  21 import org.simantics.db.exception.DatabaseException;
  22 import org.simantics.layer0.utils.binaryPredicates.IBinaryPredicate;
  23
  24 public class BinaryPredicateSubjectQuery extends BinaryPredicateInstruction {
  25
  26         public BinaryPredicateSubjectQuery(int variable0, int variable1,
  27                         IBinaryPredicate predicate) {
  28                 super(variable0, variable1, predicate);
  29         }
  30
  31         @Override
  32         public Object query(ReadGraph g, Object[] bindings) throws DatabaseException {
  33                 Resource r1 = (Resource)bindings[variable1];
  34                 Collection<Resource> result = predicate.getSubjects(g, r1);
  35                 if(result.isEmpty())
  36                         return IInstruction.FAILURE;
  37                 Iterator<Resource> it = result.iterator();
  38                 bindings[variable0] = it.next();
  39                 if(it.hasNext())
  40                         return it;
  41                 else
  42                         return null;
  43         }
  44
  45         @SuppressWarnings("unchecked")
  46         @Override
  47         public Object next(ReadGraph g, Object[] bindings, Object continuation) {
  48                 Iterator<Resource> it = (Iterator<Resource>)continuation;
  49                 if(it.hasNext()) {
  50                         bindings[variable0] = it.next();
  51                         if(it.hasNext())
  52                                 return it;
  53                         else
  54                                 return null;
  55                 }
  56                 else
  57                         return IInstruction.FAILURE;
  58         }
  59
  60         @Override
  61         public void collectVariables(TIntHashSet reads, TIntHashSet writes) {
  62                 super.collectVariables(reads, writes);
  63                 writes.add(variable0);
  64         }
  65
  66 }